In producing header and tube heat exchangers wherein a tube is united to the header at an opening in the header the clearance varies over a wide range due to worn dies used in punching the opening and manufacturing deviations generally. Because of these manufacturing deviations the molten solder material often flows out of the joint space before it can become solid within the space.
The customary way of making a solder joint whether the solder material is a lead alloy or a brazing alloy is to melt the material to a molten condition and then dip the assembly of header, plate and tubes into the molten solder. When the solder is a brazing material the melting temperature for this material can be quite high such as from 1200.degree.-2000.degree. F. depending upon the type of brazing alloy used. Under these conditions it is difficult to get the alloy into the joint by a dipping process because of the heat requirements and accelerated oxidation problems due to this high temperature. Furthermore, in order to achieve such high temperatures, it is customary to use an oxyacetylene torch and a filler wire of the appropriate alloy. Although this results in a satisfactory joint, it requires considerable time and thus is relatively costly. Also, for alloys having a melting point up toward the top of this temperature range, it is preferred to conduct the joining with the molten solder in a controlled atmosphere such as an atmosphere of nitrogen to prevent oxidation.